Overmolded optical package

ABSTRACT

An optical semiconductor package includes a substrate, a chip, a plurality of bonding wires, a window, a supporter, and an encapsulant. The chip is disposed on the substrate and has an optical element. The bonding wires are used for electrically connecting the chip to the substrate. The window is supported on the supporter and positioned over the optical element of the chip. The encapsulant is overmolded on the substrate for fixing the window and encapsulating the chip and the bonding wires.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.10/667,605, filed Sep. 23, 2003, the disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical semiconductor package, andmore particularly, to an optical package which is manufactured by theovermolding process.

2. Description of the Related Art

Referring to FIG. 1, it depicts a typically optical package 10 in priorart. The optical package 10 comprises a carrier or a substrate 12 and achip 20 mounded on the substrate 12. The substrate 12 has a sidewall 16which surrounds the substrate 12. A transparent lid 32 is mounted on thesidewall 16 by an adhesive 34 so as to form a hermetic cavity 30 andtransmit the light interacting with the chip 20. The chip 20 has opticalelements 22, such as optical sensors or imaging sensors, and is disposedin the cavity 30. The chip 20 is electrically connected to a pluralityof bonding pads 18 of the substrate 12 by a plurality of bonding wires26. The bonding pads 18 on the upper surface of the substrate 12 areelectrically connected to the solder pads 14 on the bottom surfacethereof through traces or vias 19. Because of the requirements of themanufacturing process, the substrate 12 is typically made of caramel,i.e., the substrate 12 is a kind of ceramic substrate. Furthermore, thebonding pads 18 and the solder pads 14 are disposed on the upper surfaceand the bottom surface of the substrate 12, respectively, so thesubstrate 12 is a multilayer structure.

However, the multilayer ceramic substrate 12 has long delivery leadtimes and is substantially expensive. The bonding wires 26 are connectedto the bonding pads 18 and the chip 20 which are recessed in the cavity30, so the cavity 30 or the space surrounded by the sidewall 16 has tobe large enough that the wire bond tool (not shown) can gain access tothe bonding pads 18 and the chip 20. Therefore, the cost of thesubstrate 12 is further increased. The ceramic substrate 12 is suppliedtypically as single units or small arrays and hence is assembled insingle units or small arrays, rather than large matrix arrays, so theassembly cost of the package 10 is further increased.

Accordingly, there exists a need for an optical package which can use aplanar substrate and be mass-produced to reduce the manufacturing costof the optical package.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an optical packagewith a planar substrate for mass-producing and reducing themanufacturing cost.

In order to achieve the above object, the present invention provides anoptical semiconductor package comprising a substrate, a chip, aplurality of bonding wires, a window, a supporter, and an encapsulant.The chip is disposed on the substrate and has an optical element. Thebonding wires are used for electrically connecting the chip to thesubstrate. The window is supported on the supporter and positioned overthe optical element of the chip. The encapsulant is overmolded on thesubstrate for fixing the window and encapsulating the chip and thebonding wires.

Accordingly, the substrate of the optical semiconductor package does nothave to be provided with a cavity for receiving the chip, so thesubstrate can be substantially planar and be an organic laminate orceramic substrate such that the cost of the substrate is substantiallyreduced. Furthermore, according to the manufacturing processes of thepresent invention, the substrate in matrix array can be utilized formass production and the cost of the optical semiconductor package can befurther reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages, and novel features of the invention willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawing.

FIG. 1 is a schematic cross-sectional view of an optical package in theprior art.

FIG. 2 is a schematic cross-sectional view of an optical packageaccording to an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of an optical packageaccording to another embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of an optical packageaccording to a further embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view of an optical packageaccording to a still further embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of an optical packageaccording to yet another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 2, it depicts an optical package 100 according to anembodiment of the present invention. The optical semiconductor package100 comprises a carrier or substrate 112 which is substantially planarand a chip 120 mounted on the substrate 112. The substrate 112 can beeither an organic laminate or a ceramic substrate. The chip 120 hasoptical elements 122, such as optical sensors or imaging sensors, and iselectrically connected to a plurality of bonding pads 118 of thesubstrate 112 by a plurality of bonding wires 126. The substrate 112 isfurther provided with solder balls 114 electrically connected to thebonding pads 118 for being electrically connected to an externalprinting circuit board (not shown).

A supporter 140 is disposed on the substrate 112 and is provided with ashoulder 144 for supporting and holding a window 142. Then, anencapsulant 130 is formed by overmolding or insert molding process andthe window 142 is kept in place. The window 142 is typically positionedabove the optical elements 122 of the chip 120 for receiving ortransmitting the light interacting with the optical elements 122. Theencapsulant 130 is transparent plastic, such as acrylate, nylon,polycarbonate, and the like. The supporter 140 can be made of thermalconductive material for serving as a heat sink. Alternatively, thesupporter 140 can be made of any plastic, such as PPS, Polycarbonate,LCP and the like, for reducing the cost.

The dimensions of the window 142 are designed such that the window 142does not interfere with the bonding wires 126. The dimensions and shapeof the supporter 140 depend on the height of the apexes of the bondingwires 126, the dimensions of the chip 120, and dimensions of thesubstrate 112. The space or gap between the window 142 and the opticalelements 122 of the chip 120 is optimized for overmolding and for lighttransmission. That is, the gap needs to be large enough to allow theencapsulant 130 to be filled without disturbing the bonding wires 126 orthe optical elements 122 and the gap needs to be small enough to permitsufficient transmission of light to ensure adequate operation of theoptical sensor.

The material of the window 142 depends on the optical requirements. Forexample, the material of the window 142 can be glass for the light atthe wavelength above 320 nm, or quartz for ultraviolet (UV) light. Thewindow 142 also can be made of optically transparent plastic, such asacrylate, nylon, polycarbonate, and the like.

For high volume applications, the supporter 140 and the window 142 canbe made integrally and made of plastic, such as acrylate, nylon,polycarbonate, and the like.

Now referring to FIG. 3, it depicts an optical semiconductor package 200according to another embodiment of the present invention. The opticalsemiconductor package 200 is similar to the optical semiconductorpackage 100, and the identical elements are designated with the similarreference numerals. The optical semiconductor package 200 furthercomprises two paired snapping elements including a groove 244 and aprotrusion 248 which are disposed on the supporter 240 and the window242, respectively. The protrusion 248 of the window 242 is snapped withor held in the groove 244 of the supporter 240 so as to securely fix thewindow 242 on the supporter 240 and keep the window 242 in place duringthe overmolding process. Further, the paired snapping elements, i.e. thegroove 244 and the protrusion 248, are cooperated with each other toseal the junction of the supporter 240 and the window 242 and furtherprevent the encapsulant 230 from flushing over the window 242 during theovermolding process. Besides, since the window 242 and the supporter 240are joined together, the window 242 and the supporter 240 can be handledmore easily.

Now referring to FIG. 4, it depicts an optical semiconductor package 300according to further another embodiment of the present invention. Theoptical semiconductor package 300 is similar to the opticalsemiconductor package 100, and the identical elements are designatedwith the similar reference numerals. The optical semiconductor package300 further comprises a lens 342 in place of the window 142 of theoptical semiconductor package 100. The lens 342 is used for focusing thelight on to the optical elements 322 of the chip 320 and thus increasingthe intensity of the light, thereby increasing the sensitivity of theoptical semiconductor package 300.

Now referring to FIG. 5, it depicts an optical semiconductor package 400according to still another embodiment of the present invention. Theoptical semiconductor package 400 is similar to the opticalsemiconductor package 100, and the identical elements are designatedwith the similar reference numerals. The optical semiconductor package400 further comprises a window 442 directly disposed or mounted on theoptical element 422 of the chip 420 by an adhesive 440.

The adhesive 440 is a thin layer for retaining the high opticaltransmission to the chip, and can be made of a material which is of highoptical transmission, such as acrylate. It will be apparent to thoseskilled in the art that the encapsulant 430 of the optical semiconductorpackage 400 can be made of an opaque material because the encapsulant430 does not cover the optical elements 422 of the chip 420. The window442 is further provided with a plurality of mold locks or ledges 444 forsecuring the window 442 in the encapsulant 430.

Now referring to FIG. 6, it depicts an optical semiconductor package 500according to still another embodiment of the present invention. Theoptical semiconductor package 500 is similar to the opticalsemiconductor package 200, and the identical elements are designatedwith the similar reference numerals. The optical semiconductor package500 is provided with a supporter 540 which is hermetically disposed onthe substrate 512 to form a cavity 550. The encapsulant 530 encapsulatesthe supporter 540 so as to fix the supporter 540 on the substrate 512.The chip 520 and the bonding wires 526 are positioned in the cavity 550.The window 542 is hermetically disposed on the supporter 540 fortransmitting light into and out of the cavity 550. As indicated in theforegoing description, the substrate of the optical semiconductorpackage according to the present invention is not required to have acavity for receiving the chip, so the substrate can be substantiallyplanar and be an organic laminate or ceramic substrate such that thecost of the substrate is substantially reduced. Furthermore, accordingto the manufacturing processes of the present invention, the substratein matrix array can be utilized for mass production and the cost of theoptical semiconductor package can be further reduced.

While the foregoing description and drawings represent the preferredembodiments of the present invention, it will be understood that variousadditions, modifications and substitutions may be made therein withoutdeparting from the spirit and scope of the principles of the presentinvention as defined in the accompanying claims. One skilled in the artwill appreciate that the invention may be used with many modificationsof form, structure, arrangement, proportions, materials, elements, andcomponents and otherwise, used in the practice of the invention, whichare particularly adapted to specific environments and operativerequirements without departing from the principles of the presentinvention. The presently disclosed embodiments are therefore to beconsidered in all respects as illustrative and not restrictive, thescope of the invention being indicated by the appended claims and theirlegal equivalents, and not limited to the foregoing description.

1. A method for manufacturing an optical semiconductor package,comprising the following steps of: providing a substrate; mounting achip having an optical element on the substrate; bonding a plurality ofbonding wires to the chip and the substrate for electrically connectingthe chip to the substrate; providing a supporter; disposing a window onthe supporter; mounting the supporter on the substrate; positioning thewindow corresponding to the optical element of the chip; and forming anencapsulant on the substrate for fixing the window and encapsulating thechip and the bonding wires.
 2. The method as claimed in claim 1, whereinthe encapsulant forming step further comprises the following step of:overmolding the encapsulant.
 3. The method as claimed in claim 1,further comprising the following step of: joining the window and thesupporter together.
 4. The method as claimed in claim 1, wherein thewindow is a lens.
 5. A method for manufacturing an optical semiconductorpackage, comprising the following steps of: providing a substrate;mounting a chip having an optical element on the substrate; bonding aplurality of bonding wires to the chip and the substrate forelectrically connecting the chip to the substrate; mounting a window onthe optical element of the chip; and forming an encapsulant on thesubstrate for fixing the window and encapsulating the chip and thebonding wires.
 6. The method as claimed in claim 5, wherein theencapsulant forming step further comprises the following step of:overmolding the encapsulant.
 7. The method as claimed in claim 5,wherein the window is a lens.
 8. The method as claimed in claim 5,wherein the window mounting step further comprises the following stepof: providing an adhesive for mounting the window on the optical elementof the chip.